Pickering Water Is Hard — Here's What It Costs You Each Year

Why Is Pickering Water So Hard?

Pickering gets its water from Lake Ontario, and that’s the whole story when it comes to hardness. The city is part of the Durham Region water supply system, which draws directly from the lake. That makes Pickering a surface-water city, plain and simple. There are no deep wells or limestone aquifers feeding your taps.

So where does the hardness come from if it’s not groundwater? It’s about what the water touches before it ever reaches the lake. Lake Ontario is the last stop in the Great Lakes chain, and by the time water arrives there it has traveled a long way. Rain and snowmelt run over and through the surrounding landscape, picking up minerals as they go. The Great Lakes basin sits on a lot of sedimentary rock, including limestone and dolomite. Those rocks are basically compressed calcium and magnesium carbonate. Water is an aggressive solvent, especially when it’s slightly acidic from dissolved carbon dioxide. It slowly dissolves that rock, pulling calcium and magnesium ions into solution, and those ions are exactly what we measure as hardness.

Your water tests at 7.31 grains per gallon, or 125 parts per million. That puts it right at the line between “hard” and “very hard” on the USGS scale, which classifies anything above 7 GPG as hard and above 10.5 GPG as very hard. For context, the national average is about 7.3 GPG, so Pickering sits almost exactly at the US average. You’re not imagining it if your glasses spot and your soap doesn’t lather the way it should. That’s the calcium and magnesium doing their thing.

One thing worth understanding: Lake Ontario water isn’t as hard as groundwater from deep limestone aquifers, which can easily hit 15 to 30 GPG in some regions. But it’s also not soft. The lake has had centuries of mineral accumulation from its tributaries, and the result is water that’s moderately hard by any reasonable measure. The Durham Region treats the water for safety and clarity, but hardness is a different beast. It’s not something standard municipal treatment removes, because it’s not a health issue. The EPA doesn’t regulate hardness as a health hazard at all. It’s purely aesthetic, covered under Secondary Maximum Contaminant Levels, which is why your utility doesn’t bother stripping it out.

How Pickering Compares to Nearby Cities

Pickering is part of the Durham Region’s integrated water system, and that matters for how it compares to its neighbors. The region operates a coordinated network of water treatment plants and distribution lines, all fed by Lake Ontario. So when you’re talking about hardness in Pickering, you’re talking about essentially the same water that flows through Ajax, Whitby, and Oshawa. They all draw from the same lake, through the same regional system. The hardness numbers you see in Pickering are going to be very close to what your immediate neighbors get, because it’s literally the same source.

That’s not true for every city in the Greater Toronto Area, though. Toronto itself also pulls from Lake Ontario, so its water is broadly similar in hardness. But head north or west, and the picture changes. Cities that rely on groundwater, like parts of York Region or Peel Region, can have noticeably different hardness depending on which aquifer they tap. Some of those wells pull from limestone formations and come up considerably harder than anything you’d see from the lake. Others hit sandstone or shale and run softer. It’s a crapshoot with groundwater. With Lake Ontario, you know what you’re getting, and it’s consistent.

The practical difference between Pickering and a groundwater city can be significant. On lake water at 7.31 GPG, you’re dealing with moderate hardness that will build scale over time but isn’t extreme. A city drawing from a deep limestone aquifer might see double that. The flip side is that lake water can be more uniform in temperature and quality year-round, which is a real advantage for the treatment plants. Your neighbors to the east and west along the lake shore are in the same boat. The cities that diverge are the ones that don’t share your water source at all.

If you’re comparing Pickering to Ajax specifically, you’re comparing the same water. Same lake, same regional distribution, same hardness profile. The same goes for Whitby and Oshawa. The Durham Region system is designed to move water where it’s needed, so the boundaries between municipalities don’t change what’s coming out of the tap. That’s the honest answer: your water is your neighbors’ water, and it’s all Lake Ontario water.

How does Pickering stack up against the rest of Ontario? It's hard at 7.31 GPG — Woodstock, Guelph, and Ingersoll sit nearby with different numbers. See the full hardest-water ranking for context.

See where Pickering sits on the Ontario water hardness map →

Want the broader explainer on what hardness actually is and how it behaves? Read hard water vs. soft water, explained.